In electrical inspection of, for example, a wafer, on which a great number of integrated circuits have been formed, or a circuit device, such as an electronic part such as a semiconductor device, a probe for inspection having inspection electrodes arranged in accordance with a pattern corresponding to a pattern of electrodes to be inspected of a circuit device to be inspected is used. As such a probe for inspection, may be used that, on which inspection electrodes composed of pins or blades are arranged.
When the circuit device to be inspected is a wafer, on which a great number of integrated circuits have been formed, it is however necessary to arrange a very great number of inspection electrodes upon production of a probe for inspection for inspecting the wafer, so that such a probe for inspection becomes extremely expensive. In addition, when the pitch of electrodes to be inspected is small, the production itself of the probe for inspection becomes difficult. Further, since warpage generally occurs on wafers, and the condition of the warpage varies with individual products (wafers), it is difficult in practice to stably and surely bring each of inspection electrodes of the probe for inspection into contact with a great number of electrodes to be inspected in the wafer.
For the above reasons, in recent years, a probe comprising a circuit board for inspection, on one surface of which a plurality of inspection electrodes have been formed in accordance with a pattern corresponding to a pattern of electrodes to be inspected, an anisotropically conductive sheet arranged on one surface of the circuit board for inspection and a sheet-like connector which is formed by arranging, in a flexible insulating sheet, a plurality of electrode structures each extending through in a thickness-wise direction of the insulating sheet, and arranged on the anisotropically conductive sheet, has been proposed as a probe for inspection for inspecting integrated circuits formed on a wafer (see, for example, the following Prior Art 1).
FIG. 49 is a cross-sectional view illustrating the construction of a conventional exemplary probe for circuit inspection, which is equipped with a circuit board for inspection, an anisotropically conductive sheet and a sheet-like connector. In this probe for circuit inspection, is provided the circuit board 85 for inspection having, on one surface thereof, a great number of inspection electrodes 86 formed in accordance with a pattern corresponding to a pattern of electrodes to be inspected of a circuit board to be inspected. The sheet-like connector 90 is arranged on one surface of the circuit board 85 for inspection through the anisotropically conductive sheet 80.
The anisotropically conductive sheet 80 is a sheet exhibiting conductivity only in its thickness-wise direction or having pressure-sensitive conductive conductor parts exhibiting conductivity only in its thickness-wise direction when it is pressurized in the thickness-wise direction. As such anisotropically conductive sheets, those of various structures have been known. For example, the following Prior Art 2, and the like disclose an anisotropically conductive sheet (hereinafter referred to as “dispersion type anisotropically conductive sheet”) obtained by uniformly dispersing metal particles in an elastomer, and the following Prior Art 3, and the like disclose an anisotropically conductive sheet (hereinafter referred to as “uneven distribution type anisotropically conductive sheet”) obtained by unevenly distributing particles of a conductive magnetic substance in an elastomer to form a great number of conductive parts extending in a thickness-wise direction thereof and insulating parts for mutually insulating them. Further, the following Prior Art 4, and the like disclose an uneven distribution type anisotropically conductive sheet with a difference in level defined between the surface of each conductive part and an insulating part.
The sheet-like connector 90 has a flexible insulating sheet 91 composed of, for example a resin, and is formed by arranging, in this insulating sheet 91, a plurality of electrode structures 95 each extending in a thickness-wise direction of the insulating sheet in accordance with the pattern corresponding to the pattern of the electrodes to be inspected of the circuit board to be inspected. Each of the electrode structures 95 is formed by integrally connecting a projected front-surface electrode part 96 exposed to a front surface of the insulating sheet 91 and a plate-like back-surface electrode part 97 exposed to a back surface of the insulating sheet 91 to each other through a short circuit part 98 extending through in the thickness-wise direction of the insulating sheet 91.
Such a sheet-like connector 90 is generally produced in the following manner.
As illustrated in FIG. 50(a), a laminate material 90A obtained by forming a metal layer on one surface of an insulating sheet 91 is first provided, and through-holes 98H each extending through in a thickness-wise direction of the insulating sheet 91 are formed in the insulating sheet 91 as illustrated in FIG. 50(b).
As illustrated in FIG. 50(c), a resist film 93 is then formed on the metal layer 92 on the insulating sheet 91, and an electroplating treatment is conducted by using the metal layer 92 as a common electrode, whereby metal deposit is filled into the through-holes 98H in the insulating sheet 91 to form short circuit parts 98 integrally joined to the metal layer 92, and at the same time, projected front-surface electrode parts 96 integrally joined to the respective short circuit parts 98 are formed on the front surface of the insulating sheet 91.
Thereafter, the resist film 93 is removed from the metal layer 92, and as illustrated in FIG. 50(d), a resist film 94A is formed on the surface of the insulating sheet 91 including the front-surface electrode parts 96, and moreover resist film portions 94B are formed on the metal layer 92 in accordance with a pattern corresponding to a pattern of back-surface electrode parts to be formed. The metal layer 92 is subjected to an etching treatment to remove exposed portions of the metal layer 92, thereby forming back-surface electrode parts 97 as illustrated in FIG. 50(e), thus resulting in the formation of the electrode structures 95.
The resist film 94A formed on the insulating sheet 91 and front-surface electrode parts 96 is removed, and at the same time the resist film portions 94B formed on the back-surface electrode parts 97 are removed, thereby obtaining the sheet-like connector 90.
In the above-described probe for inspection, the front-surface electrode parts 96 of the electrode structures 95 in the sheet-like connector 90 are arranged on the surface of a circuit board to be inspected, for example, a wafer so as to be located on electrodes to be inspected of the wafer. In this state, the wafer is pressed by the probe for inspection, whereby the anisotropically conductive sheet 80 is pressed by the back-surface electrode parts 97 of the electrode structures 95 in the sheet-like connector 90, and in the anisotropically conductive sheet 80, conductive paths are thereby formed between the back-surface electrode parts 97 and the inspection electrodes 86 of the circuit board 85 for inspection in the thickness-wise direction of the anisotropically conductive sheet 80. As a result, electrical connection of the electrodes to be inspected of the wafer to the inspection electrodes 86 of the circuit board 85 for inspection is achieved. In this state, necessary electrical inspection as to the wafer is then performed.
According to such a probe for inspection, the anisotropically conductive sheet is deformed according to the degree of warpage of the wafer when the wafer is pressed by the probe for inspection, so that good electrical connection to a great number of the respective electrodes to be inspected in the wafer can be surely achieved.
However, the above-described probe for inspection involves the following problems.
In the step of forming the short circuit parts 98 and front-surface electrode parts 96 in the production process of the sheet-like connector, the metallic deposit by the electroplating isotropically grows. Therefore, in the resulting front-surface electrode part 96, a distance w from a periphery of the front-surface electrode part 96 to a periphery of the short circuit part 98 becomes equivalent to the projected height h of the front-surface electrode part 96 as illustrated in FIG. 51. Accordingly, the diameter R of the resulting front-surface electrode part 96 exceeds twice of the projected height h and becomes considerably large. When the electrodes to be inspected in the circuit board to be inspected are minute and arranged at an extremely small pitch, a clearance between electrode structures 95 adjacent to each other thus cannot be sufficiently retained. As a result, in the resulting sheet-like connector, the flexibility by virtue of the insulating sheet 91 is lost, so that it is difficult to achieve stable electrical connection to the circuit board to be inspected.
In addition, since it is difficult in practice to supply a current even in current density distribution to the overall surface of the metal layer 92 in the electroplating treatment, the growing rate of the metallic deposit varies with individual through-holes 98H in the insulating sheet 91 due to the unevenness of the current density distribution, so that a wide scatter occurs on the projected height h of the front-surface electrode parts 96 formed and the distance w from the periphery of the front-surface electrode part 96 to the periphery of the short circuit part 98, i.e., the diameter R. If a wide scatter occurs on the projected height h of the front-surface electrode parts 96, stable electrical connection to the circuit board to be inspected becomes difficult. If a wide scatter occurs on the diameter of the front-surface electrode parts 96 on the other hand, there is a possibility that adjacent front-surface electrode parts may short-circuit each other.
In the above, a means of making the projected height h of the front-surface electrode parts 96 small, and a means of making the diameter (smallest length in the case where the sectional form is not circular) r of the short circuit parts 98 small, i.e., making the diameter of the through-holes 98H in the insulating sheet 91 small are considered as means for making the diameter of the resulting front-surface electrode parts 96 small. In the sheet-like connector obtained by the former means, however, it is difficult to surely achieve stable electrical connection to the electrodes to be inspected. On the other hand, in the latter means, the formation itself of the short circuit parts 98 and front-surface electrode parts 96 by the electroplating treatment becomes difficult.
In order to solve such problems, a sheet-like connector obtained by arranging a great number of electrode structures each having a tapered front-surface electrode part, the diameter of which becomes gradually small from the base end toward the tip end, is proposed in the following Prior Art 5 and Prior Art 6.
The sheet-like connector described in the following Prior Art 5 is produced in the following manner.
As illustrated in FIG. 52(a), a laminate material 90B obtained by forming a resist film 93A and a front surface-side metal layer 92A on a front surface of an insulating sheet 91 in this order, and laminating a back surface-side metal layer 92B on a back surface of the insulating sheet 91 is provided. As illustrated in FIG. 52(b), through-holes each linked to each of the back surface-side metal layer 92B, insulating sheet 91 and resist film 93A in the laminate material 90B and extending in a thickness-wise direction of the laminate material are formed, thereby forming, in the back surface of the laminate material 90B, recesses 90K for forming electrode structures, which each have a tapered form fitted to a short circuit part and a front-surface electrode part of an electrode structure to be formed. As illustrated in FIG. 52(c), a plating treatment is then conducted by using the front surface-side metal layer 92A in the laminate material 90B as an electrode, thereby filling a metal into the recesses 90K for forming electrode structures to form front-surface electrode parts 96 and short circuit parts 98. The back surface-side metal layer in the laminate material is then subjected to an etching treatment to remove a part thereof, thereby forming back-surface electrode parts 97 as illustrated in FIG. 52(d), thus resulting in provision of the sheet-like connector.
The sheet-like connector described in the following Prior Art 6 is produced in the following manner.
As illustrated in FIG. 53(a), a laminate material 90C obtained by forming a front surface-side metal layer 92A on a front surface of an insulating sheet material 91A having a thickness greater than that of an insulating sheet in a sheet-like connector to be formed and laminating a back surface-side metal layer 92B on a back surface of the insulating sheet material 91A is provided. As illustrated in FIG. 53(b), through-holes each linked to each of the back surface-side metal layer 92B and insulating sheet material 91A in the laminate material 90C and extending in a thickness-wise direction of the laminate material are formed, thereby forming, in the back surface of the laminate material 90C, recesses 90K for forming electrode structures, which each have a tapered form fitted to a short circuit part and a front-surface electrode part of an electrode structure to be formed. A plating treatment is then conducted by using the front surface-side metal layer 92A in the laminate material 90C as an electrode, thereby filling a metal into the recesses 90K for forming electrode structures as illustrated in FIG. 53(c) to form front-surface electrode parts 96 and short circuit parts 98. Thereafter, the front surface-side metal layer 92A in the laminate material 90C is removed, and the insulating sheet material 91A is subjected to an etching treatment to remove the portion on the front surface side of the insulating sheet material, thereby forming an insulating sheet 91 having a necessary thickness- and exposing the front-surface electrode parts 96 as illustrated in FIG. 53(d). The back surface-side metal layer 92B is then subjected to an etching treatment, thereby forming back-surface electrode parts, thus resulting in provision of the sheet-like connector.
According to such a sheet-like connector, the front-surface electrode parts small in diameter and high in projected height can be formed in a state that a clearance between front-surface electrodes of electrode structures adjacent to each other has been sufficiently retained, since the front-surface electrode parts are in a tapered form. In addition, the front-surface electrode parts of the respective electrode structures are formed by using the recesses for forming the electrode structures formed in the laminate material as cavities, so that the electrode structures narrow in a scatter of projected height of the front-surface electrode parts can be provided.
In these sheet-like connectors, however, the diameter of the front-surface electrode parts in the electrode structures is equivalent to or smaller than the diameter of the short circuit parts, i.e., the diameter of the through-holes formed in the insulating sheet, so that the electrode structures fall off from the back surface of the insulating sheet, resulting in the difficulty of actually using such a sheet-like connector.
Prior Art 1: Japanese Patent Application Laid-Open No. 231019/1995;
Prior Art 2: Japanese Patent Application Laid-Open No. 93393/1976;
Prior Art 3: Japanese Patent Application Laid-Open No. 147772/1978;
Prior Art 4: Japanese Patent Application Laid-Open No. 250906/1986;
Prior Art 5: Japanese Patent Application Laid-Open No. 326378/1999;
Prior Art 6: Japanese Patent Application Laid-Open No. 2002-196018.